The present invention relates generally to receiver dryers for refrigeration and other air conditioning systems.
A receiver dryer is a common component of a refrigeration (or more generally, air conditioning) system, and receives excess refrigerant in the cooling cycle, separates vapor refrigerant from liquid refrigerant, and removes water and particulate matter.
One type of receiver dryer includes a cylindrical canister with inlet and outlet fittings at an upper end which allow refrigerant to flow into and out of the canister. One of the fittings (typically the outlet fitting) is connected at its internal end to a pick-up tube, which extends downwardly through the canister to the lower end. Layers of filters and desiccant material surround the pick-up tube along its length. Refrigerant is directed into the inlet fitting and drains down through the filter pads and desiccant material to the bottom of the canister. The filter pads and desiccant material remove particles and other impurities from the refrigerant. The refrigerant then flows upwardly through the pick-up tube to the outlet fitting.
The desiccant material can be provided in a fabric bag, or can be loose. Fabric bags have some advantages as they are easy to assemble in the canister of the receiver dryer. Fabric bags, however are more expensive to manufacture, and do not allow flexibility in using the bags in a wide variety of applications. For example, each bag is designed for a specific application and has a predetermined volume, porosity, material and desiccant composition, etc. To change the structure, material or composition of the desiccant bag for other applications, new bags typically must be manufactured. This can require tooling changes and ordering of new fabric and desiccant material, all of which can be time-consuming and expensive. Stocks of different sizes and types of desiccant bags also typically have to be kept on hand which can increase storage and inventory costs, and hence the over-all cost of the receiver/dryer.
In some applications it is therefor desirable to use loose desiccant material for the receiver dryer. Such loose desiccant material can be less expensive to purchase and is easily adaptable to a wide variety of applications (i.e., does not have restrictions as to form or composition). The desiccant can just be added (poured) into the canister in the desired amount, with no additional labor or material costs.
In using loose desiccant material, however, it can be difficult to assemble the receiver dryer. The lower end wall of the receiver dryer is typically initially secured to or formed in one piece with the lower end of the canister. The pick-up tube is typically pre-assembled with the upper end cap, however, in so doing, the desiccant must be introduced into the canister before the pick-up tube and end cap subassembly is installed, or else the end cap blocks the easy filling of the canister, as well as the introduction of components such as the upper baffle and filter pad. It can be difficult (or even impossible) to introduce the pick-up tube into the canister when the loose desiccant is randomly dispersed in the canister, as it is not desirable to force the pick-up tube through the loose desiccant material. The desiccant can also flow through the pick-up tube opening in the lower baffle before the pick-up tube is inserted into the canister, and thus enter the lower, quiescent area of the receiver/dryer.
One solution is shown and described in U.S. Pat. No. 5,910,165, where the loose desiccant is poured into the receiver dryer after a lower baffle, filter pad and a short desiccant tube are assembled in the canister. The lower baffle and filter pad closely surround the desiccant tube in fluid-tight relation thereto. The baffle and desiccant tube can also be formed together in one piece (unitary). An upper filter pad and baffle are then located in the canister, in fluid-tight relation to the desiccant tube, to enclose the loose desiccant. The pick-up tube, attached to the upper end cap, is then inserted through the desiccant tube and the upper end cap is then secured (welded, soldered, etc.) to the open end of the canister.
U.S. Pat. No. 5,910,165 describes inlet and outlet ports formed in the upper end cap. It is believed that in some applications, it would be necessary or desirable to have at least the inlet port formed in the lower end wall. This can be due to space requirements or plumbing of the liquid lines. While some refrigeration devices with bottom inlets are known (see, e.g., Rasovich, U.S. Pat. No. 3,177,689; and Cochran, U.S. Pat. No. 4,665,716), it is believed that such devices have had certain drawbacks, and none provide a receiver dryer with sufficient filtering and water removal capabilities for many current applications.
Moreover, providing a receiver dryer with a bottom inlet requires an inlet tube to direct the refrigerant to the upper portion of the canister, where the refrigerant can then drain down through the filter pads, baffles and desiccant to the lower end of the canister, where it is then drawn out through the pick-up tube. In so doing, however, similar issues arise in pouring the loose desiccant material into the receiver dryer during assembly.
Thus, it is believed that there is a demand for a further improved receiver dryer having a bottom inlet with improved removal of particles and other impurities. Still further, it is believed that there is a demand for a receiver dryer with a bottom inlet which can accept loose desiccant material to reduce the cost of the receiver dryer, and which is still easy and cost effective to assemble.
The present invention provides a new and unique receiver dryer with a bottom inlet, which accepts loose desiccant material. The receiver dryer is simple to assemble and cost-effective to produce.
According to the present invention, the receiver dryer has a canister with a lower end wall. The lower end wall can be formed in one piece (unitary) with the sidewall of the canister by drawing, impacting spinning, or other appropriate forming of the canister, or can be a separate piece secured to the sidewall of the canister such as by welding, soldering, etc. An inlet port is provided in the lower end wall, and an inlet tube is fluidly sealed to the inlet port. The inlet tube extends inwardly in the canister to a point near the upper end of the canister. The inlet tube can also extend through the inlet port exteriorly to the canister, or can be formed in one piece (unitary) with the lower end wall.
A desiccant tube assembly, having a pair of relatively short, longitudinally-extending, adjacent tubes, is then located over the inlet tube, toward the lower end of the canister. The inlet tube is received within a first of the tubes of the desiccant tube assembly, and has a fluid-tight seal therewith. A circular lower baffle is provided at the lower end of the desiccant tube assembly. The baffle is preferably formed together (e.g., molded) in one piece (unitary) with the lower end of the desiccant tube assembly, although it can also be a separate component secured to the desiccant tube assembly in an appropriate manner. The baffle preferably has a fluid-tight seal with the interior sidewall of the canister. A circular lower filter pad, with a pair of openings for the desiccant tubes, is supported against the lower baffle. Loose desiccant is then poured into the canister in the desired amount, and is supported by the lower baffle and filter pad.
An upper circular filter pad and baffle, both of which also have a pair of openings for the desiccant tube assembly, support the upper end of the desiccant material. The upper baffle also preferably has a fluid-tight seal with the desiccant tube assembly and the canister. The upper and lower baffles (and filter pads) prevent vibration or movement of the desiccant material.
An upper end cap, with a pick-up tube secured thereto, is then assembled with the canister. The pick-up tube can be crimped, coined, staked or otherwise secured to the upper end cap, or can be formed together with the end cap in one piece (unitary). The pick-up tube is inserted into the other opening in the upper baffle, filter pads and through the other tube of the desiccant tube assembly. The pick-up tube also preferably has a fluid-tight seal with the desiccant tube. The upper end cap is then secured to the canister with a fluid-tight seal, such as by brazing, welding, soldering, etc.
The pick-up tube can be bent or curved, such that the lower end of the pick-up tube is aligned with the desiccant tube, but the upper end is connected in an off-center relation to the end cap. This allows flexibility in connecting exterior components to the end cap. The inlet tube can have the same configuration as the pick-up tube. The upper end cap and pick-up tube can also be first secured to the canister sidewalls, and the desiccant material poured in from the bottom of the receiver dryer (when inverted) before the lower end cap and inlet tube are secured to the canister sidewall. This provides flexibility in assembling the receiver dryer.
As described above, the present invention provides a receiver dryer with a bottom inlet which is simple and cost-effective to manufacture. Loose desiccant material, rather than desiccant bags, can be used with the receiver dryer, which reduces the over-all cost of the receiver dryer and provides flexibility in tailoring the amount, composition, etc. of desiccant material to the particular application.
Further features of the present invention will become apparent to those skilled in the art upon reviewing the following specification and attached drawings.